Manpage of csflag
Section: User Commands (1)
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csflag - CARMA shadowing flagging
CSFLAG is a MIRIAD task which flags correlations where an array
of variable sized antennae could geometrically shadow each other.
An array of antenna diameters must be given, the number of antenna
must be exactly equal that in the dataset.
Although UVFLAG can also be used, the current visibility format
does not easily allow for variable sized antennae shadowing
calculations. Although this program was designed for CARMA,
it should work for any heterogenous array.
It is also possible to define a sub-array, and find out
if antennas from the remaining antennas are shadowing the antennas
in the sub-array. With the caveat of not knowing exactly where the
other antennae are pointing, a swept volume algorithm is used for
Note that this program only SETS flags, never unsets. Multiple
runs of csflag with decreasing values of cfraction= will thus
NOT have the effect you think it might have. Make a backup
of your flags/wflags files if you want to recover.
uvflag vis= flagval=flag options=noapply
to see how many active flags you have now.
The input visibility file to be flagged. No default.
Array of diameters (in m) for each antenna. By default
all antenna are the same, and equal the antdiam found in
the dataset. No default. See also carma= below for a
Default: not used
Boolean, if set to true, the 23-antenna CARMA array is loaded
in the antdiam array. Also it is then assumed the first 6
are OVRO dishes (assumed 10.4m), the next 9 are BIMA
(assumed 6.1m), and final 8 for the SZA 3.5m dishes
If selected, it will also print out the number of records
flagged for O-O, B-B and O-B (labeled O/H/C) for 15-ants
and labeled O/H/C/S/10/6 for 23-ants
This will also load the Swept Volume descriptors.
The default is true.
Special CARMA option to multiply the antdiam array for
OVRO and BIMA dishes by. Two or three numbers are expected here,
depending if SZA was set or found to be true:
fraction for OVRO, that for BIMA, and optionally that for SZA.
You normally want this leave this at 1, but can experiment with
smaller values to try and keep some partially shadowed data;
but check your calibrator(s) how well this is expected to work.
Another cheat, like cfraction, to make the swept volume smaller/bigger
by this factor
Specify the sub-array (if there is such a thing) for use in the
Swept Volume method of flagging. If you specify 0, it will first
scan the visibility data to find out which ants are present, and
will use these for the sub-array. All other antennas in the
antenna position array will then be used in the Swept Volume
Default: not used.
By default only baselines from the dataset itself are investigated
if an antenna of a pair is shadowed. By setting all=true you can
allow the other antennae in the array to be taken into account.
This is a very conservative algorithm, and is generally not needed
in most circumstances. Usually the sarray= keyword is sufficient to
compute how the non-subarray antannea are shadowing the subarray
in the current dataset.
Also known as the Swept Volume method (Eric Leitch)
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Time: 18:35:38 GMT, July 05, 2011